Glycogen Synthase Kinase 3 beta, Recombinant, Human (GSK3b)

Glycogen Synthase Kinase-3 (GSK-3) is a serine/threonine kinase that was first characterized by its role in intermediary metabolism. The enzyme is the mammalian homolog of the zeste-white3 (shaggy) homeotic gene of Drosophila melanogaster and has been implicated in the regulation of the c-Jun/AP-1 transcription factor. In mammals, this protein serine kinase is encoded by two related genes called GSK-3a (51kD) and b (46kD). Genetic and biochemical evidence now indicates that GSK-3 plays a role in intracellular signaling pathways. For example, during insulin and growth factor signaling the GSK-3 beta isoform becomes phosphorylated on its N-terminal serine-9 residue, presumably by either the action of MAPKAP Kinase-1 (p90 S6 kinase, Rsk-2) or p70 S6 kinase. Such phosphorylation of GSK-3 blocks its ability to phosphorylate c-Jun, protein phosphatase inhibitor 2 or the GSK-3 substrate peptide. Quality Control: MS Tryptic Fingerprint: Confirmed identity as GSK3b with 52% amino acid coverage of the translated native sequence listed in the protocol., GSK3b Kinase Assay: 2-6ng phosphorylated 20uM Glycogen Synthase Peptide 2, Phosphorylated (Substrate) (G8170-26) in the assay described in protocol. Specific Activity: ~900u/mg. , Unit Definition: One unit equals 1nmole phosphate incorporated into 20uM Glycogen Synthase Peptide 2, Phosphorylated (Substrate) (G8170-26) per minute at 30°C with a final ATP concentration of 100uM. Handling Recommendations: Rapidly thaw the vial under cold water. Immediately place on ice. Aliquot unused material into pre-chilled microcentrifuge tubes. Immediately snap-freeze the vials in liquid nitrogen prior to re-storage at -70°C. Storage and Stability: May be stored at 4°C for short-term only. For long-term storage, aliquot and store at -70°C. Aliquots are stable for 6 months at -70°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.